Since the energy required for driving sailboats in water is afforded from the wind, the geometrical form and size of the a sail which confronts the wind force become very crucial with respect to the sailing capability of the boat. On the other hand, the stable floating of the sailboat on the water depending on the wind force is directly related to the location of the boat's center of gravity.
The wind exerting throughout the sail's surface area generates force and this force produces a moment so that the boat is forced to tip to various directions as a result of this moment. As a matter of fact, if no balancing effect is provided, the risk occurs in which such a boat may assume a position that would sink it into the water under the effect of this moment. The balancing of many sailboats against external moments is ensured by means of keels provided at the underwater hull of such boats.
Keels of the type in the art are mounted to the hull in a fixed manner, i.e. statically. A static keel may cause the boat to loose its stability against varying wind loads effecting the sails and worsening the boat's tipping angle, finally preventing the boat from moving fast as desired.